Meaning of jí:
集
to gather; to collect
Tāmen měi zhōurì zài gōngyuán lǐ jí huì.
他们每周日在公园里集会。
They gather in the park every Sunday.
Tā hěn xǐhuān jíyóu.
她很喜欢集邮。
She really likes to collect stamps.
collected works
Zhè běn shū shì lìshǐ rénwù de wén jí.
这本书是历史人物的文集。
This book is a collection of historical figures' writings.
classifier for sections of a TV series etc: episode
Wǒ zuì xǐhuān zhè bù diànshìjù de dì èr jí.
我最喜欢这部电视剧的第二集。
My favorite is the second episode of this TV series.